User blog comment:Devilmaycry01/Devil May Cry still lives!/@comment-190.79.23.253-20150110080114/@comment-24.244.32.228-20150125024928

Who knows? We never saw Nero or Vergil interact onscreen, nor did we see them claim that they did not know the other, so how do we know whether they knew each other or not?

Also, some of Vergil's techniques are spells, such as the Summoned Swords and Dark Slayer Style.